Current File : //usr/local/include/google/protobuf/util/field_comparator.h
// Protocol Buffers - Google's data interchange format
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Defines classes for field comparison.
#ifndef GOOGLE_PROTOBUF_UTIL_FIELD_COMPARATOR_H__
#define GOOGLE_PROTOBUF_UTIL_FIELD_COMPARATOR_H__
#include <cstdint>
#include <map>
#include <string>
#include <vector>
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/port_def.inc>
namespace google {
namespace protobuf {
class Message;
class EnumValueDescriptor;
class FieldDescriptor;
namespace util {
class FieldContext;
class MessageDifferencer;
// Base class specifying the interface for comparing protocol buffer fields.
// Regular users should consider using or subclassing DefaultFieldComparator
// rather than this interface.
// Currently, this does not support comparing unknown fields.
class PROTOBUF_EXPORT FieldComparator {
public:
FieldComparator();
virtual ~FieldComparator();
enum ComparisonResult {
SAME, // Compared fields are equal. In case of comparing submessages,
// user should not recursively compare their contents.
DIFFERENT, // Compared fields are different. In case of comparing
// submessages, user should not recursively compare their
// contents.
RECURSE, // Compared submessages need to be compared recursively.
// FieldComparator does not specify the semantics of recursive
// comparison. This value should not be returned for simple
// values.
};
// Compares the values of a field in two protocol buffer messages.
// Returns SAME or DIFFERENT for simple values, and SAME, DIFFERENT or RECURSE
// for submessages. Returning RECURSE for fields not being submessages is
// illegal.
// In case the given FieldDescriptor points to a repeated field, the indices
// need to be valid. Otherwise they should be ignored.
//
// FieldContext contains information about the specific instances of the
// fields being compared, versus FieldDescriptor which only contains general
// type information about the fields.
virtual ComparisonResult Compare(const Message& message_1,
const Message& message_2,
const FieldDescriptor* field, int index_1,
int index_2,
const util::FieldContext* field_context) = 0;
private:
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(FieldComparator);
};
// Basic implementation of FieldComparator. Supports three modes of floating
// point value comparison: exact, approximate using MathUtil::AlmostEqual
// method, and arbitrarily precise using MathUtil::WithinFractionOrMargin.
class PROTOBUF_EXPORT SimpleFieldComparator : public FieldComparator {
public:
enum FloatComparison {
EXACT, // Floats and doubles are compared exactly.
APPROXIMATE, // Floats and doubles are compared using the
// MathUtil::AlmostEqual method or
// MathUtil::WithinFractionOrMargin method.
// TODO(ksroka): Introduce third value to differentiate uses of AlmostEqual
// and WithinFractionOrMargin.
};
// Creates new comparator with float comparison set to EXACT.
SimpleFieldComparator();
~SimpleFieldComparator() override;
void set_float_comparison(FloatComparison float_comparison) {
float_comparison_ = float_comparison;
}
FloatComparison float_comparison() const { return float_comparison_; }
// Set whether the FieldComparator shall treat floats or doubles that are both
// NaN as equal (treat_nan_as_equal = true) or as different
// (treat_nan_as_equal = false). Default is treating NaNs always as different.
void set_treat_nan_as_equal(bool treat_nan_as_equal) {
treat_nan_as_equal_ = treat_nan_as_equal;
}
bool treat_nan_as_equal() const { return treat_nan_as_equal_; }
// Sets the fraction and margin for the float comparison of a given field.
// Uses MathUtil::WithinFractionOrMargin to compare the values.
//
// REQUIRES: field->cpp_type == FieldDescriptor::CPPTYPE_DOUBLE or
// field->cpp_type == FieldDescriptor::CPPTYPE_FLOAT
// REQUIRES: float_comparison_ == APPROXIMATE
void SetFractionAndMargin(const FieldDescriptor* field, double fraction,
double margin);
// Sets the fraction and margin for the float comparison of all float and
// double fields, unless a field has been given a specific setting via
// SetFractionAndMargin() above.
// Uses MathUtil::WithinFractionOrMargin to compare the values.
//
// REQUIRES: float_comparison_ == APPROXIMATE
void SetDefaultFractionAndMargin(double fraction, double margin);
protected:
// Returns the comparison result for the given field in two messages.
//
// This function is called directly by DefaultFieldComparator::Compare.
// Subclasses can call this function to compare fields they do not need to
// handle specially.
ComparisonResult SimpleCompare(const Message& message_1,
const Message& message_2,
const FieldDescriptor* field, int index_1,
int index_2,
const util::FieldContext* field_context);
// Compare using the provided message_differencer. For example, a subclass can
// use this method to compare some field in a certain way using the same
// message_differencer instance and the field context.
bool CompareWithDifferencer(MessageDifferencer* differencer,
const Message& message1, const Message& message2,
const util::FieldContext* field_context);
// Returns FieldComparator::SAME if boolean_result is true and
// FieldComparator::DIFFERENT otherwise.
ComparisonResult ResultFromBoolean(bool boolean_result) const;
private:
// Defines the tolerance for floating point comparison (fraction and margin).
struct Tolerance {
double fraction;
double margin;
Tolerance() : fraction(0.0), margin(0.0) {}
Tolerance(double f, double m) : fraction(f), margin(m) {}
};
// Defines the map to store the tolerances for floating point comparison.
typedef std::map<const FieldDescriptor*, Tolerance> ToleranceMap;
friend class MessageDifferencer;
// The following methods get executed when CompareFields is called for the
// basic types (instead of submessages). They return true on success. One
// can use ResultFromBoolean() to convert that boolean to a ComparisonResult
// value.
bool CompareBool(const FieldDescriptor& /* unused */, bool value_1,
bool value_2) {
return value_1 == value_2;
}
// Uses CompareDoubleOrFloat, a helper function used by both CompareDouble and
// CompareFloat.
bool CompareDouble(const FieldDescriptor& field, double value_1,
double value_2);
bool CompareEnum(const FieldDescriptor& field,
const EnumValueDescriptor* value_1,
const EnumValueDescriptor* value_2);
// Uses CompareDoubleOrFloat, a helper function used by both CompareDouble and
// CompareFloat.
bool CompareFloat(const FieldDescriptor& field, float value_1, float value_2);
bool CompareInt32(const FieldDescriptor& /* unused */, int32_t value_1,
int32_t value_2) {
return value_1 == value_2;
}
bool CompareInt64(const FieldDescriptor& /* unused */, int64_t value_1,
int64_t value_2) {
return value_1 == value_2;
}
bool CompareString(const FieldDescriptor& /* unused */,
const std::string& value_1, const std::string& value_2) {
return value_1 == value_2;
}
bool CompareUInt32(const FieldDescriptor& /* unused */, uint32_t value_1,
uint32_t value_2) {
return value_1 == value_2;
}
bool CompareUInt64(const FieldDescriptor& /* unused */, uint64_t value_1,
uint64_t value_2) {
return value_1 == value_2;
}
// This function is used by CompareDouble and CompareFloat to avoid code
// duplication. There are no checks done against types of the values passed,
// but it's likely to fail if passed non-numeric arguments.
template <typename T>
bool CompareDoubleOrFloat(const FieldDescriptor& field, T value_1, T value_2);
FloatComparison float_comparison_;
// If true, floats and doubles that are both NaN are considered to be
// equal. Otherwise, two floats or doubles that are NaN are considered to be
// different.
bool treat_nan_as_equal_;
// True iff default_tolerance_ has been explicitly set.
//
// If false, then the default tolerance for floats and doubles is that which
// is used by MathUtil::AlmostEquals().
bool has_default_tolerance_;
// Default float/double tolerance. Only meaningful if
// has_default_tolerance_ == true.
Tolerance default_tolerance_;
// Field-specific float/double tolerances, which override any default for
// those particular fields.
ToleranceMap map_tolerance_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(SimpleFieldComparator);
};
// Default field comparison: use the basic implementation of FieldComparator.
#ifdef PROTOBUF_FUTURE_BREAKING_CHANGES
class PROTOBUF_EXPORT DefaultFieldComparator final
: public SimpleFieldComparator
#else // PROTOBUF_FUTURE_BREAKING_CHANGES
class PROTOBUF_EXPORT DefaultFieldComparator : public SimpleFieldComparator
#endif // PROTOBUF_FUTURE_BREAKING_CHANGES
{
public:
ComparisonResult Compare(const Message& message_1, const Message& message_2,
const FieldDescriptor* field, int index_1,
int index_2,
const util::FieldContext* field_context) override {
return SimpleCompare(message_1, message_2, field, index_1, index_2,
field_context);
}
};
} // namespace util
} // namespace protobuf
} // namespace google
#include <google/protobuf/port_undef.inc>
#endif // GOOGLE_PROTOBUF_UTIL_FIELD_COMPARATOR_H__
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